(a) Field of the Invention
The present invention is related to a heterostructure field effect transistor (HFET), and more particularly, to a group IIIA-VA HFET and method of fabricating the same.
(b) Description of the Prior Art
Today Schottky barrier diodes are used in many power switching applications such as switch mode power supplies (SMPS), converters, and inverters. Engineers and scientists have used heterostructure FET (HFET) or high-electron-mobility transistor (HEMT) to create Schottky barrier diodes. A heterostructure FET (HFET) or a high-electron-mobility transistor (HEMT) is a field-effect transistor (FET) incorporating a junction between two materials with different band gaps (i.e. a heterojunction) as the channel instead of a doped region as is the case generally for MOSFET. Most conventional power components are based on Si-based materials, because Si material is relatively inexpensive and is considered a well-understood material, but due to the limitations of the physical properties of the Si material, its role as a power component has reached a performance bottleneck in energy conversion efficiency. To this end, group IIIA-VA material has come to the forefront in the adaptation for usage as power device or in power switching applications.
At the moment, the device characteristics for group IIIA-VA have been recognized to be superior to other semiconductor materials, so as to be considered as viable candidate for used as power device up to a certain performance level, due to having a higher breakdown voltage, faster operating speed and lower operating resistance.
In many power device applications, it is desirable to improve forward OFF-state blocking performance and to have a reverse blocking capability. For power converters used in electric vehicles, the power switch must be protected from a reverse-battery connection, or from damage due to inadvertent biasing drain terminal and a negative bias voltage.